<?php

namespace App\Lib;

use App\Lib\Options;
use Dxw\CIDR\IPAddress;
use Dxw\CIDR\IPv4Address;
use Dxw\CIDR\IPv4Range;
use Dxw\CIDR\IPv6Address;
use Dxw\CIDR\IPv6Range;

abstract class AdminSecure
{
    /**
     * Private ipV4 CIDR list
     *
     * @var array
     */
    private static $private_ip_v4_cidr_list = [
        '10.0.0.0/8', '172.16.0.0/12', '192.168.0.0/16'
    ];

    /**
     * Private ipV4 CIDR loopback
     *
     * @var string
     */
    private static $private_ip_v4_loopback_cidr = '127.0.0.0/8';

    /**
     * Private ipV6 CIDR list
     *
     * @var array
     */
    private static $private_ip_v6_cidr_list = [
        'fd00::/8'
    ];

    /**
     * Private ipV6 CIDR loopback
     *
     * @var string
     */
    private static $private_ip_v6_loopback_cidr = '::1/128';

    /**
     * Private options
     *
     * @var \App\Lib\Options|null
     */
    private static $options = null;

    /**
     * Check if ip is private
     *
     * @param \Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address $ip_address
     * @return boolean
     */
    public static function ipIsPrivate($ip_address): bool
    {
        return \get_class($ip_address) === IPv4Address::class ?
            self::ipV4IsPrivate($ip_address) : self::ipV6IsPrivate($ip_address);
    }

    /**
     * Fetch client IP
     *
     * @return \Dxw\CIDR\IPv4Address|\Dxw\CIDR\IPv6Address
     * @throws \Exception  If the ip is invalid.
     */
    public static function fetchClientIp()
    {
        // ! REVERSE PROXY HACK.
        $ip = request()->server('HTTP_X_FORWARDED_FOR') ?? request()->getClientIp();
        $ip = IPAddress::Make($ip);

        if ($ip->isErr()) {
            throw new \Exception(\trans('Client IP not valid ') . $ip->getErr());
        }
        return $ip->unwrap();
    }

    /**
     * Check if ipV4 is private
     *
     * @param \Dxw\CIDR\IPv4Address $ipv4_address
     * @return boolean
     */
    private static function ipV4IsPrivate(IPv4Address $ipv4_address): bool
    {
        return \collect(self::$private_ip_v4_cidr_list)
            ->concat([self::$private_ip_v4_loopback_cidr])
            ->map(function (string $ipv4_cidr) {
                return IPv4Range::Make($ipv4_cidr)->unwrap();
            })
            ->reduce(function ($initial, IPv4Range $ipv4_range) use ($ipv4_address) {
                return $initial || $ipv4_range->containsAddress($ipv4_address);
            });
    }

    /**
     * Check if ipV6 is private
     *
     * @param \Dxw\CIDR\IPv6Address $ipv6_address
     * @return boolean
     */
    private static function ipV6IsPrivate(IPv6Address $ipv6_address): bool
    {
        return \collect(self::$private_ip_v6_cidr_list)
            ->concat([self::$private_ip_v6_loopback_cidr])
            ->map(function (string $ipv6_cidr) {
                return IPv6Range::Make($ipv6_cidr)->unwrap();
            })
            ->reduce(function ($initial, IPv6Range $ipv6_range, IPv6Address $ipv6_address) {
                return $initial || $ipv6_range->containsAddress($ipv6_address);
            });
    }

    /**
     * Get Admin secure options
     *
     * @return \App\Lib\Options
     */
    public static function getOptions(): Options
    {
        if (!self::$options) {
            self::$options = new Options(\config('admin-secure'));
        }
        return self::$options;
    }
}